The Orientation of Cladocera to Polarized Light

Cladocera orient to polarized light by swimming at right angles to the plane of vibration. Similar behavior is described for other organisms. A mechanism for detecting the plane of vibration of polarized light is developed for the simple ocellus of the water mite, applied in detail to the cladoceran eye, and extended to the arthropod compound eye. The orientation by Cladocera is discussed in relation to discrete shafts of light in partly shaded ponds and to skylight in the open water.